An example of this type of monitoring device-for the brake devices of railroad cars is disclosed in the prior art of, for example, Japanese Laid-Open Utility Model Application H2-96354. Also, an example of delayed-action control of brake devices for railroad cars is the art disclosed in Japanese Laid-Open Patent Application S63-10024. Such monitoring device is described in connection with a railway car that does not employ delayed-action control, but an example of its application to a brake device with such delayed-action control is described in conjunction with FIGS. 4 through 6.
In FIG. 4, the composite car consists of both a locomotive and a trailer car. In the locomotive, there is a brake controller 1 which outputs a brake power command signal e.sub.1 via a brake command line 10, according to the manipulator variable of handle 1a, and a standard brake power generator 3, respectively, that generates a brake power command signal e.sub.5 required by the trailer car and the brake power command signal e.sub.4 required by the locomotive. This brake power command signal e.sub.1 is based on each signal of the locomotive and trailer car load response apparatus 2 and 20. The brake power generator 3 generates a composite brake power command signal e.sub.2 by adding these together.
Electrical brake device 4 generates electrical brake power based on this composite brake power command signal e.sub.2 and outputs electrical brake power equivalent signal e.sub.3 corresponding to the electrical brake power actually generated. A computer 25 computes the supplementary pneumatic brake power which is the deficit (difference) between the actual electrical brake power and the overall brake power from such composite brake power signal e.sub.2 and the electrical brake power equivalent signal e.sub.3, and distributes this supplementary pneumatic brake power to the trailer car and the locomotive based on brake power signal e.sub.5 required by the trailer car and brake power signal e.sub.4 required by the locomotive, and, respectively, outputs them as a locomotive supplementary pneumatic brake power command signal e.sub.8 and trailer car supplementary pneumatic brake power command signal e.sub.9 to the locomotive pneumatic brake device 6 and trailer car pneumatic brake device 21.
In such locomotive pneumatic brake device 6 and the trailer car pneumatic brake device 21, compressed air is expelled from electropneumatic valves 7 and 22, respectively, according to each supplementary pneumatic brake power command signal e.sub.8 and e.sub.9. This compressed air is supplied to the brake cylinders 9 and 24 after their flow rates are amplified by relay valves 8 and 23 and pneumatic brake power corresponding to the difference between the electrical brake power and the overall brake power is thereby generated and distributed to the trailer car and the locomotive.
Meanwhile, pressure-detecting switches S3 and S5 which are opened and closed according to the pressure in such brake cylinders 9 and 24 are respectively provided on the trailer car monitoring device 28 and the locomotive monitoring device 13 which, respectively, have trailer car pneumatic brake device 21 and locomotive pneumatic brake device 6. The pressure-detecting switches S3 and S5 are connected to branch lines 15 and 30 of a brake deficit check line 11 which is connected to deficit check switch S1 in such brake controller 1.
Also, electrical brake device 4 is connected to interlock relays 14 and 29 of deficit check circuits 60 and 61 and during the generation of electrical braking, pressure is applied to the interlock relays 14 and 29 and such contact points open. Next, each contact point of these interlock relays 14 and 29 is connected to each timer circuit 17 and 32 and, furthermore, such timer circuits 17 and 32 are connected to each memory circuit 18 and 33.
In this case, such pressure-detecting switches S3 and S5 are closed when the pressure in brake cylinders 9 and 24 is below the pneumatic brake deficit detection pressure p.sub.1 and they are open when it exceeds the pneumatic brake deficit detection pressure P.sub.1. Also, the deficit check switch S1 of such brake controller 1 is closed when the manipulator variable of handle 1a is above a specific amount, and the detection pressure of pressure-detecting switches S3 and S5 is set according to that specific amount.
On the other hand, when the handle 1a of brake controller 1 is operated in the brake position (i.e.,above a specific amount), while an electrical braking force is being generated at such electrical brake device 4, because the coil of the interlock relay 14 is magnetized and its contact points are in the open (cut-off) position, the signal from pneumatic brake check line 11 is not input into the timer circuit 17 and the locomotive monitoring device 13 is released. But if such electrical brake power becomes invalid, interlock relay 14 is demagnetized and its contact points are closed, so that if the pressure in the brake cylinder 9 is below pneumatic brake power deficit detection pressure p.sub.1, pressure-detecting switch S3 closes so that the signal from pneumatic brake deficit check line 11 is input to timer circuit 17 and storage circuit 18 and the locomotive monitoring device 13 detects the pneumatic brake power deficit after the time limit of timer circuit 17. The operation of trailer car monitoring device 28 is exactly the same as the above operation of the locomotive monitoring device 13 and its description is therefore omitted.
Next, the delayed-action control of the above-mentioned brake device is described with particular reference to FIG. 5 and FIG. 6. In FIG. 5, the composite brake power command signal e.sub.2 is given limiter characteristics by a limiter (not shown in FIG. 4) before being input into such electrical brake device 4, shown in FIG. 4. That is to say, the electrical brake force command is limited to below the maximum grip brake force H of the locomotive. In this way, when the electrical brake action rate (referred to hereinafter as the electrical control rate) is 100%, the locomotive is subjected to the entire brake force of the composite car when the composite brake force command signal e.sub.2 is less than the maximum grip braking force H of the locomotive, and when the composite brake force command signal e.sub.2 is larger than the maximum grip brake force H, the trailer car is subjected to the pneumatic braking force of the deficit while the locomotive continues to support the maximum grip brake force and the electrical brake force of the locomotive is used to the maximum limit.
Next, computer 25 of FIG. 4, performs the computation shown in FIG. 6 regarding the distribution of supplementary pneumatic braking accompanying a-change in the electrical control rate. FIG. 6A is the case of low notching of the brake commands, in other words, when the composite brake power command signal e.sub.2 is below the maximum grip brake power H.
In FIG. 6A as the electrical control rate decreases below 100%, the deficit of the electrical brake power equivalent signal e.sub.3 with respect to the composite brake power command signal e.sub.2 is first taken up by the supplementary brake force (=trailer car supplementary pneumatic brake force command signal e.sub.9) of the trailer car (range R2) and when the electrical control rate further decreases and the brake force required by the locomotive (=brake power command signal e.sub.4 required by the locomotive), the deficit begins to be taken up by the supplementary pneumatic brake force (=locomotive supplementary pneumatic brake force command signal e.sub.8) of the locomotive (range R1).
FIG. 6B is the situation during high brake command notching, in other words, the case when the composite brake power command signal e.sub.2 is larger than the maximum grip brake power H. In this case, the amount by which the maximum grip braking force H of the locomotive is exceeded is taken up by the supplementary pneumatic brake force e.sub.9 of the trailer car and is, otherwise, the same as FIG. 6A.
It so happens that in the above-mentioned brake monitoring device, as regards the deficit monitoring of pneumatic brake power, when electrical brake power is not generated, the electrical control availability signal e.sub.7 from electrical brake device 4 is cleared. First interlock-relay 14 and second interlock relay 29 of locomotive monitoring device 13 and trailer car monitoring device 28 are demagnetized and their contact points are opened. The brake deficit check circuits 60 and 61 are closed if a voltage is applied to the pneumatic brake check line 11 and deficit monitoring of the pneumatic brakes of the locomotive and trailer car is performed.
On the other hand, when electrical brake power is generated, electrical control availability signal e.sub.7 is output from the electrical brake device 4. First interlock relay 14 and second interlock relay 29 are magnetized and their contact points are opened and even if a voltage is applied to pneumatic brake check line 11, pneumatic brake deficit check circuits 60 and 61 are not closed and deficit monitoring of the pneumatic brakes of the locomotive and trailer car is not performed.
This has the following disadvantages. That is, it has the disadvantage that in cases where electrical brake power is generated but the electrical brake power is not supplied to the brake power of the trailer car (range R1 of FIG. 6), in the event of some fault developing in the pneumatic brake of the trailer car (for example, a faulty relay valve, a drop in braking pressure and so on) regardless of the actual brake deficit state, since the pneumatic brake deficit monitoring of the trailer car is not performed as mentioned above, this brake deficit state is not detected.
As a result, there has been the problem that the stopping distance of the cars has lengthened. In particular, this effect is large in composite cars where the M/T ratio is smaller compared with conventional methods by using induction motors as the main motor. This effect can be fatal with regard to high speed/high density driving which requires high speed deceleration.
The present invention has been made in view of these disadvantages of such prior art and its objective is to provide a brake monitoring device with improved safety in a delayed-action control brake device wherein electrical brake force is generated but deficit monitoring of the pneumatic brake system of the trailer car is performed when electrical brake power is not supplied to the brake power of the trailer car.